The linear vestibular-occular reflex (LVOR) provides unequaled opportunities to dissect sensory-motor integrative function, both at the behavioral and neurophysiologic level, because the system can be so radically modulated (e.g., reversals in direction) by easily controlled behavioral conditions (e.g., fixation distance and eccentricity). These attributes are exploited by cellular neurophysiologic studies which determine where along VOR neural circuits the specific modulations of reflex formation described above occur, and how and where different subsets of the VOR (i.e., AVOR driven by different canals, LVORs driven by different sets of otolith efferents and canal-otolith interactions) combine. Clearly, all sensory influences during eye movements must converge upon ocular motor neurons, the final neural output path to the muscles themselves, but interactions between different vestibular endorgans also occur in the vestibular neurons within VOR pathways. How complex are these interactions, what is their role, and what are the behavioral implications of the shared VOR elements? Do eye position signals, known to exist in vestibular nuclear neurons, provide a unique and necessary substrate for VOR modulation? If so, do they entail only conjugate signals, or do they include disconjugate or even monocular eye position information needed to generate the disconjugate VOR response observed occasionally? This project addresses these questions using single cell recording techniques in awake behaving monkeys. Attention will focus on VOR-related neurons in the vestibular nuclei, and on motor neurons and internuclear neurons in the abducens oculormotor nuclei.